With the development of information and communication technology, various wireless communication technologies have been developed. Among these technologies, a wireless local area network (WLAN) denotes technology for allowing wireless access to the Internet in homes, businesses or specific service areas using a mobile terminal such as a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), a smart phone, or a tablet PC, based on radio frequency (RF) technology.
Standards for WLAN technology have been developed as Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards. WLAN technology conforming to the IEEE 802.11a standard is operated based on an orthogonal frequency division multiplexing (OFDM) scheme, and is capable of providing a maximum data rate of 54 Mbps in a 5 GHz band. WLAN technology conforming to the IEEE 802.11b standard is operated based on a direct sequence spread spectrum (DSSS) scheme, and is capable of providing a maximum data rate of 11 Mbps in a 2.4 GHz band. WLAN technology conforming to the IEEE 802.11g standard is operated based on the OFDM or DSSS scheme, and is capable of providing a maximum data rate of 54 Mbps in a 2.4 GHz band.
WLAN technology conforming to the IEEE 802.11n standard is operated based on the OFDM scheme in a 2.4 GHz band and a 5 GHz band, and is capable of providing a maximum data rate of 300 Mbps for four spatial streams when a Multiple-Input Multiple-Output OFDM (MIMO-OFDM) scheme is used. WLAN technology conforming to the IEEE 802.11n standard may support a channel bandwidth of up to 40 MHz and is capable of providing a maximum data rate of 600 Mbps in that case.
As the popularization of such WLAN technology has been activated and applications using WLANs have been diversified, the requirement for new WLAN technology that supports throughput higher than that of existing WLAN technology is increasing. Very high throughput (VHT) WLAN technologies are technologies proposed to support data processing speeds of 1 Gbps or more. Among these technologies, WLAN technology conforming to the IEEE 802.11ac standard is technology for providing very high throughput (VHT) in a band of 6 GHz or less, and WLAN technology conforming to the IEEE 802.11ad standard is technology for providing VHT in a 60 GHz band.
In addition, standards for various WLAN technologies have been established, and technologies are being developed. As representatives thereof, WLAN technology conforming to the IEEE 802.11af standard is technology defined for the operation of a WLAN in TV white space, WLAN technology conforming to the IEEE 802.11ah is technology defined to support a large number of terminals operating on low power, and WLAN technology conforming to the IEEE 802.11ai standard is technology defined for fast initial link setup (FILS) in a WLAN system. Recently, in a congested environment in which multiple base stations and terminals are present, the standardization of an IEEE 802.11 high-efficiency WLAN (HEW), aimed at improving frequency use efficiency, is ongoing.
In such a system based on WLAN technology, any terminal may function as a relay device for relaying data transmitted between a master access point and an end terminal. A master basic service set (BSS), configured by the master access point, and a relay BSS, configured by the relay device, use the same channel. However, since terminals belonging to respective BSSs refer to different beacon frames, access to the channel by terminals belonging to the relay BSS is not restricted by a restricted access window (RAW) parameter set (RPS) included in a beacon frame transmitted by the master access point.